1. Field of the Invention
The present invention relates to a precursor of a heat resistant resin, a heat resistant resin, an insulating film and a semiconductor device. More particularly, the present invention relates to a precursor providing a polybenzoxazole resin which exhibits excellent electric, mechanical and physical properties, in particular, excellent properties under heating, and is advantageously used for insulating interlayer films and films for protecting surfaces in semiconductors, insulating interlayer films of multi-layer circuits, cover coats of flexible copper clad laminates, solder resist films and liquid crystal-aligning films, a polybenzoxazole resin which is obtained from the above precursor and has the above characteristics, an insulating film comprising the polybenzoxazole resin and a semiconductor device comprising the insulating film.
2. Description of Related Art
As the insulating interlayer films, films of oxides (films of SiOx) prepared in accordance with the chemical vapor deposition process (the CVD process) are mainly used at present. However, inorganic insulating films such as films of oxides have a great permittivity. To achieve a high speed and a high performance of semiconductors, an insulating film having a low permittivity is desired and films of organic materials have been examined as the candidates. As the organic material used for semiconductors, heat resistant resins having excellent electric, mechanical and physical properties are proposed.
For example, application of polybenzoxazole resins as the above heat resistant resin has been attempted. To obtain a polybenzoxazole resin, in general, a precursor of the polybenzoxazole resin is prepared from a bisaminophenol compound and a dicarboxylic acid compound. An article such as a film is prepared by using the precursor and the precursor formed into the article is then converted into a polybenzoxazole resin. Examples of the polybenzoxazole resin include polybenzoxazole resins synthesized from 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxybiphenyl and terephthalic acid and polybenzoxazole resins synthesized from 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxy-biphenyl and 4,4xe2x80x2-biphenyldicarboxylic acid.
As described above, heat resistance can be easily improved by providing a rigid skeleton structure to a resin. However, this causes a decrease in the solubility of a precursor of the resin into organic solvents and working of the resin such as preparation of a film in accordance with a coating process becomes very difficult. On the other hand, for example, a polybenzoxazole resin prepared from 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane and isophthalic acid can be worked into various shapes since the precursor is soluble in organic solvents. However, when the above precursor is converted into a polybenzoxazole resin, heat resistance of the obtained resin tends to be inferior to the former polybenzoxazole resins.
Since the above heat resistant resins are examined as materials to replace inorganic compounds in applications such as insulating interlayer films in semiconductors, the improvement in the heat resistance of the heat resistant resins is increasingly required. It is necessary that heat resistance be further improved while the resin is kept soluble in organic solvents so that excellent processability is maintained.
The present invention has objects of providing a precursor of a polybenzoxazole resin which exhibits excellent processability due to excellent solubility in solvents and, after ring closure, excellent heat stability in applications and provides a resin which exhibits excellent electric, physical and mechanical properties and is advantageously used for insulating interlayer films of semiconductor devices; a heat resistant resin which is obtained from the above precursor and has the above characteristics; an insulating film comprising the polybenzoxazole resin; and a semiconductor device comprising the insulating film.
As the result of extensive studies by the present inventors to achieve the above objects, it was found that a precursor of a polybenzoxazole resin having a specific structure which is obtained by introducing a three-dimensionally crosslinking functional group into the structure of the main chain maintains the solubility in organic solvents and can be converted into a resin having high heat resistance by heating due to a three-dimensional structure formed by a combination of a conventional condensation reaction (the ring closure reaction with elimination of water) and the crosslinking reaction. The present invention has been completed based on the knowledge.
The present invention provides:
(1) A precursor of a polybenzoxazole resin which comprises a crosslinking group in a molecule;
(2) A precursor of a polybenzoxazole resin described in (1), which comprises a structure represented by general formula [1]: 
wherein R1 to R4 each independently represent hydrogen atom or a monovalent organic group, X represents a tetravalent group selected from groups represented by following formulae (A), two groups represented by X may be the same with or different from each other, Y represents at least one divalent group selected from groups represented by following formulae (B), (C), (D) and (E), Z represents a divalent group selected from groups represented by following formulae (F), m and n each represent an integer satisfying relations of m greater than 0, nxe2x89xa70, 2xe2x89xa6m+nxe2x89xa61,000 and 0.05xe2x89xa6m/(m+n)xe2x89xa61 and arrangement of repeating units may be a block arrangement or a random arrangement;








wherein X1 in formulae (A) and (F) represents a divalent group selected from groups represented by following formulae (G):

R in formulae (C) represents an alkyl group or a monovalent group selected from groups represented by formulae (H):

and hydrogen atoms on a benzene ring in groups represented by Formulae (A), (B), (C), (D), (E), (F) and (G) may be substituted with at least one atom or group selected from alkyl groups having 1 to 4 carbon atom, fluorine atom and trifluoromethyl group;
(3) A polybenzoxazole resin which is obtained from a precursor of a polybenzoxazole resin described in any of (1) and (2) by a condensation reaction and a crosslinking reaction;
(4) An insulating film which comprises a polybenzoxazole resin described in (3); and
(5) A semiconductor device which comprises at least one film which is selected from insulating interlayer films in multi-layer wiring and films for protecting surfaces and comprises an in sulating film described in (4).
The precursor of a polybenzoxazole resin of the present invention comprises a crosslinking group in the molecule. Examples of the crosslinking group include substituent groups which can be three-dimensionally crosslinked such as ethynyl group, substituted ethynyl groups, internal acetylene group, biphenylene group, cyanato group, maleimide group, nadimide group and propargyl group. The precursor may have one or more crosslinking groups in the molecule.
As the precursor of a polybenzoxazole described above, compounds comprising the structure represented by the above general formula [1] are preferable.
The precursor of a polybenzoxazole resin comprising the structure represented by general formula [1] can be obtained in accordance with a conventional process such as the acid chloride process, the activated ester process and the condensation reaction in the presence of an agent for condensation with elimination of water such as polyphosphoric acid and dicyclohexylcarbodiimide using at least one compound selected from bisaminophenol compounds having a tetravalent group selected from the groups represented by formulae (A) and at least one dicarboxylic acid having a crosslinking group selected from the divalent groups represented by formulae (B), (C), (D) and (E). A combination of the above dicarboxylic acid and a dicarboxylic acid having a divalent group selected from the groups represented by formulae (F) may be used as the dicarboxylic acid. A highly heat resistant resin can also be obtained by forming an interpenetrating network from a combination of a polyamide comprising at least one skeleton structure represented by general formula [1], such as the ethynyl structure, the phenylethynyl structure, the alkylethynyl structures, the biphenylene structure and the internal acetylene structure, and a conventional polyamide without crosslinking groups, i.e., without the crosslinking reactivity. A polyamide which does not have the ethynyl skeleton structure, the phenylethynyl skeleton structure, the alkylethynyl skeleton structures, the biphenylene skeleton structure or the internal acetylene skeleton structure can be obtained in accordance with a process similar to the processes described above using at least one compound selected from bisaminophenol compounds having a tetravalent group selected from the groups represented by formulae (A) and at least one compound selected from dicarboxylic acids having a divalent group selected from the groups represented by formulae (F).
Examples of the bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A) include 2,4-diaminoresorcinol, 4,6-diaminoresorcinol, 2,2-bis(3-amino-4-hydroxy-phenyl)hexafluoropropane, 2,2-bis(4-amino-3-hydroxyphenyl)hexafluoro-propane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis(4-amino-3-hydroxyphenyl)propane, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxydiphenylsulfone, 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxydiphenylsulfone, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxy-biphenyl, 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxybiphenyl, 9,9-bis(4-((4-amino-3-hydroxy)phenoxy)phenyl)fluorene, 9,9-bis(4-((3-amino-4-hydroxy)-phenoxy)phenyl)fluorene, 9,9-bis((4-amino-3-hydroxy)phenyl)fluorene, 9,9-bis((3-amino-4-hydroxy)phenyl)fluorene, 9,9-bis(4-((4-amino-3-hydroxy)-phenoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-((3-amino-4-hydroxy)-phenoxy)-3-phenylphenyl)fluorene, 9,9-bis((2-amino-3-hydroxy-4-phenyl)-phenyl)fluorene, 9,9-bis((2-hydroxy-3-amino-4-phenyl)phenyl)fluorene, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxydiphenyl ether, 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxydi-phenyl ether, 2,2-bis(3-amino-4-hydroxy-2-trifluoromethylphenyl)propane, 2,2-bis(4-amino-3-hydroxy-2-trifluoromethylphenyl)propane, 2,2-bis(3-amino-4-hydroxy-5-trifluoromethylphenyl)propane, 2,2-bis(4-amino-3-hydroxy-5-trifluoromethylphenyl)propane, 2,2-bis(3-amino-4-hydroxy-6-trifluoromethylphenyl)propane, 2,2-bis(4-amino-3-hydroxy-6-trifluoromethylphenyl)propane, 2,2-bis(3-amino-4-hydroxy-2-trifluoromethylphenyl)hexafluoropropane, 2,2-bis(4-amino-3-hydroxy-2-trifluoromethylphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxy-5-trifluoromethylphenyl)hexafluoropropane, 2,2-bis(4-amino-3-hydroxy-5-trifluoromethylphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxy-6-trifluoromethylphenyl)hexafluoropropane, 2,2-bis(4-amino-3-hydroxy-6-trifluoromethylphenyl)hexafluoropropane, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxy-2,2xe2x80x2-bis(trifluoromethyl)biphenyl, 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxy-2,2xe2x80x2-bis(trifluoromethyl)biphenyl, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxy-5,5xe2x80x2-bis(trifluoromethyl)biphenyl, 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxy-5,5xe2x80x2-bis(trifluoromethyl)biphenyl, 3,3xe2x80x2-diamino-4,4xe2x80x2-dihydroxy-6,6xe2x80x2-bis(trifluoromethyl)biphenyl and 4,4xe2x80x2-diamino-3,3xe2x80x2-dihydroxy-6,6xe2x80x2-bis(trifluoromethyl)biphenyl. The above compounds may be used singly or in combination of two or more.
Examples of the dicarboxylic acid having an ethynyl skeleton structure having a divalent group selected from the groups represented by formulae (B) include 3-ethynylphthalic acid, 4-ethynylphthalic acid, 2-ethynylisophthalic acid, 4-ethynylisophthalic acid, 5-ethynylisophthalic acid, 2-ethynylterephthalic acid, 3-ethynylterephthalic acid, 5-ethynylterephthalic acid, 2-ethynyl-1,5-naphthalenedicarboxylic acid, 3-ethynyl-1,5-naphthalenedicarboxylic acid, 4-ethynyl-1,5-naphthalene-dicarboxylic acid, 1-ethynyl-2,6-naphthalenedicarboxylic acid, 3-ethynyl-2,6-naphthalenedicarboxylic acid, 4-ethynyl-2,6-naphthalenedicarboxylic acid, 2-ethynyl-1,6-naphthalenedicarboxylic acid, 3-ethynyl-1,6-naphthalenedicarboxylic acid, 4-ethynyl-1,6-naphthalenedicarboxylic acid, 5-ethynyl-1,6-naphthalenedicarboxylic acid, 7-ethynyl-1,6-naphthalene-dicarboxylic acid, 8-ethynyl-1,6-naphthalenedicarboxylic acid, 3,3xe2x80x2-diethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 4,4xe2x80x2-diethynyl-2,2xe2x80x2-biphenyl-dicarboxylic acid, 5,5xe2x80x2-diethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 6,6xe2x80x2-diethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-diethynyl-3,3xe2x80x2-biphenyl-dicarboxylic acid, 4,4xe2x80x2-diethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 5,5xe2x80x2-diethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 6,6xe2x80x2-diethynyl-3,3xe2x80x2-biphenyl-dicarboxylic acid, 2,2xe2x80x2-diethynyl-4,4xe2x80x2-biphenyldicarboxylic acid, 3,3xe2x80x2-diethynyl-4,4xe2x80x2-biphenyldicarboxylic acid, 2,2-bis(2-carboxy-3-ethynylphenyl)propane, 2,2-bis(2-carboxy-4-ethynylphenyl)propane, 2,2-bis(2-carboxy-5-ethynylphenyl)propane, 2,2-bis(2-carboxy-6-ethynyl-phenyl)propane, 2,2-bis(3-carboxy-2-ethynylphenyl)propane, 2,2-bis(3-carboxy-4-ethynylphenyl)propane, 2,2-bis(3-carboxy-5-ethynylphenyl)-propane, 2,2-bis(3-carboxy-6-ethynylphenyl)propane, 2,2-bis(4-carboxy-2-ethynylphenyl)propane, 2,2-bis(4-carboxy-3-ethynylphenyl)propane, 2,2-bis(2-carboxy-4-ethynylphenyl)hexafluoropropane, 2,2-bis(3-carboxy-5-ethynylphenyl)hexafluoropropane, 2,2-bis(4-carboxy-2-ethynylphenyl)-hexafluoropropane, 2,2-bis(4-carboxy-3-ethynylphenyl)hexafluoropropane, 4-ethynyl-1,3-dicarboxylcyclopropane, 5-ethynyl-2,2-dicarboxy-cyclopropane, structural isomers of 1,3-bis(4-carboxyphenoxy)-5-ethynylbenzene, structural isomers of 1,3-bis(4-carboxyphenyl)-5-ethynylbenzene, 5-(3-ethynylphenoxy)isophthalic acid, 5-(1-ethynylphenoxy)isophthalic acid, 5-(2-ethynylphenoxy)isophthalic acid, 2-(1-ethynylphenoxy)terephthalic acid, 2-(2-ethynylphenoxy)terephthalic acid, 2-(3-ethynylphenoxy)terephthalic acid, 5-(1-ethynylphenyl)-isophthalic acid, 5-(2-ethynylphenyl)isophthalic acid, 5-(3-ethynylphenyl)-isophthalic acid, 2-(1-ethynylphenyl)terephthalic acid, 2-(2-ethynylphenyl)terephthalic acid and 2-(3-ethynylphenyl)terephthalic acid. However the dicarboxylic acid is not limited to the compounds described as the examples. The above compound may be used singly or in combination of two or more. The above compounds may be used in combination with two or more bisaminophenyl compounds.
Examples of the substituent represented by R in the divalent groups represented by formulae (C) used in the present invention include alkyl groups and monovalent groups represented by formulae (H) such as phenyl group, biphenyl group, naphthyl group, anthryl group, quinolyl group and quinoxalyl group. Examples of the dicarboxylic acid having the phenylethynyl skeleton structure in which the substituent represented by R is phenyl group include 3-phenylethynylphthalic acid, 4-phenylethynylphthalic acid, 2-phenylethynylisophthalic acid, 4-phenylethynylisophthalic acid, 5-phenylethynylisophthalic acid, 2-phenylethynylterephthalic acid, 3-phenylethynylterephthalic acid, 2-phenylethynyl-1,5-naphthalenedicarboxylic acid, 3-phenylethynyl-1,5-naphthalenedicarboxylic acid, 4-phenylethynyl-1,5-naphthalene-dicarboxylic acid, 1-phenylethynyl-2,6-naphthalenedicarboxylic acid, 3-phenylethynyl-2,6-naphthalenedicarboxylic acid, 4-phenylethynyl-2,6-naphthalenedicarboxylic acid, 2-phenylethynyl-1,6-naphthalene-dicarboxylic acid, 3-phenylethynyl-1,6-naphthalenedicarboxylic acid, 3-phenylethynyl-1,6-naphthalenedicarboxylic acid, 4-phenylethynyl-1,6-naphthalenedicarboxylic acid, 5-phenylethynyl-1,6-naphthalene-dicarboxylic acid, 7-phenylethynyl-1,6-naphthalenedicarboxylic acid, 8-phenylethynyl-1,6-naphthalenedicarboxylic acid, 3,3xe2x80x2-diphenylethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 4,4xe2x80x2-diphenylethynyl-2,2xe2x80x2-biphenyl-dicarboxylic acid, 5,5xe2x80x2-diphenylethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 6,6xe2x80x2-diphenylethynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-diphenylethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 4,4xe2x80x2-diphenylethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 5,5xe2x80x2-diphenylethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 6,6xe2x80x2-diphenylethynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-diphenylethynyl-4,4xe2x80x2-biphenyldicarboxylic acid, 3,3xe2x80x2-diphenylethynyl-4,4xe2x80x2-biphenyldicarboxylic acid, 2,2-bis(2-carboxy-3-phenylethynylphenyl)propane, 2,2-bis(2-carboxy-4-phenylethynylphenyl)propane, 2,2-bis(2-carboxyl-5-phenylethynyl-phenyl)propane, 2,2-bis(2-carboxy-6-phenylethynylphenyl)propane, 2,2-bis(3-carboxy-2-phenylethynylphenyl)propane, 2,2-bis(3-carboxy-4-phenylethynylphenyl)propane, 2,2-bis(3-carboxy-5-phenylethynylphenyl)-propane, 2,2-bis(3-carboxy-6-phenylethynylphenyl)propane, 2,2-bis(4-carboxy-2-phenylethynylphenyl)propane, 2,2-bis(4-carboxy-3-phenyl-ethynylphenyl)propane, 2,2-bis(2-carboxy-4-phenylethynylphenyl)-hexafluoropropane, 2,2-bis(3-carboxy-5-phenylethynylphenyl)hexafluoro-propane, 2,2-bis(4-carboxy-2-phenylethynylphenyl)hexafluoropropane, 2,2-bis(4-carboxy-2-phenylethynylphenyl)hexafluoropropane, 4-phenyl-ethynyl-1,3-dicarboxycyclopropane, 5-phenylethynyl-2,2-dicarboxy-cyclopropane, structural isomers of 1,3-bis(4-carboxyphenoxy)-5-phenylethynylbenzene, structural isomers of 1,3-bis(4-carboxyphenyl)-5-phenylethynylbenzene, 5-(1-phenylethynylphenoxy)isophthalic acid, 5-(2-phenylethynylphenoxy)isophthalic acid, 5-(3-phenylethynylphenoxy)-isophthalic acid, 2-(1-phenylethynylphenoxy)terephthalic acid, 2-(2-phenylethynylphenoxy)terephthalic acid, 2-(3-phenylethynylphenoxy)-terephthalic acid, 5-(1-phenylethynylphenyl)isophthalic acid, 5-(2-phenylethynylphenyl)isophthalic acid, 5-(3-phenylethynylphenyl)-isophthalic acid, 2-(1-phenylethynylphenyl)terephthalic acid, 2-(2-phenylethynylphenyl)terephthalic acid and 2-(3-phenylethynylphenyl)-terephthalic acid.
Examples of the dicarboxylic acid having the alkylethynyl skeleton structure in which the substituent represented by R is an alkyl group include 3-hexynylphthalic acid, 4-hexynylphthalic acid, 2-hexynyl-isophthalic acid, 4-hexynylisophthalic acid, 5-hexynylisophthalic acid, 2-hexynylterephthalic acid, 3-hexynylterephthalic acid, 2-hexynyl-1,5-naphthalenedicarboxylic acid, 3-hexynyl-1,5-naphthalenedicarboxylic acid, 4-hexynyl-1,5-naphthalenedicarboxylic acid, 1-hexynyl-2,6-naphthalene-dicarboxylic acid, 3-hexynyl-2,6-naphthalenedicarboxylic acid, 4-hexynyl-2,6-naphthalenedicarboxylic acid, 2-hexynyl-1,6-naphthalenedicarboxylic acid, 3-hexynyl-1,6-naphthalenedicarboxylic acid, 4-hexynyl-1,6-naphthalenedicarboxylic acid, 5-hexynyl-1,6-naphthalenedicarboxylic acid, 7-hexynyl-1,6-naphthalenedicarboxylic acid, 8-hexynyl-1,6-naphthalene-dicarboxylic acid, 3,3xe2x80x2-dihexynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 4,4xe2x80x2-dihexynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 5,5xe2x80x2-dihexynyl-2,2-biphenyl-dicarboxylic acid, 6,6xe2x80x2-dihexynyl-2,2xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-dihexynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 4,4xe2x80x2-dihexynyl-3,3xe2x80x2-biphenyl-dicarboxylic acid, 5,5xe2x80x2-dihexynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 6,6xe2x80x2-dihexynyl-3,3xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-dihexynyl-4,4xe2x80x2-biphenyl-dicarboxylic acid, 3,3xe2x80x2-dihexynyl-4,4xe2x80x2-biphenyldicarboxylic acid, 2,2-bis(2-carboxy-3-hexynylphenyl)propane, 2,2-bis(2-carboxy-4-hexynylphenyl)-propane, 2,2-bis(2-carboxy-5-hexynylphenyl)propane, 2,2-bis(2-carboxy-6-hexynylphenyl)propane, 2,2-bis(3-carboxy-2-hexynylphenyl)propane, 2,2-bis(3-carboxy-4-hexynylphenyl)propane, 2,2-bis(3-carboxy-5-hexynyl-phenyl)propane, 2,2-bis(3-carboxy-6-hexynylphenyl)propane, 2,2-bis(4-carboxy-2-hexynylphenyl)propane, 2, 2-bis(4-carboxy-3-hexynylphenyl)-propane, 2,2-bis(2-carboxy-4-hexynylphenyl)hexafluoropropane, 2,2-bis(3-carboxy-5-hexynylphenyl)hexafluoropropane, 2,2-bis(4-carboxy-2-hexynyl-phenyl)hexafluoropropane, 4-hexynyl-1,3-dicarboxycyclopropane, 5-hexynyl-2,2-dicarboxy-cyclopropane, structural isomers of 1,3-bis(4-carboxyphenoxy)-5-hexynylbenzene, structural isomers of 1,3-bis(4-carboxyphenyl)-5-hexynylbenzene, 5-(3-hexynylphenoxy)isophthalic acid, 5-(1-hexynyl-phenoxy)isophthalic acid, 5-(2-hexynylphenoxy)isophthalic acid, 2-(1-hexynylphenoxy)terephthalic acid, 2-(2-hexynylphenoxy)terephthalic acid, 2-(3-hexynylphenoxy)terephthalic acid, 5-(1-hexynylphenyl)isophthalic acid, 5-(2-hexynylphenyl)isophthalic acid, 5-(3-hexynylphenyl)isophthalic acid, 2-(1-hexynylphenyl)terephthalic acid, 2-(2-hexynylphenyl)-terephthalic acid and 2-(3-hexynylphenyl)terephthalic acid. However, the dicarboxylic acid is not limited to the compounds described as the examples.
The above compounds may be used singly or in combination of two or more. The above compounds may be used in combination with two or more bisaminophenyl compounds.
Examples of the dicarboxylic acid having the biphenylene skeleton structure having the divalent group selected from the groups represented by formulae (D) include 1,2-biphenylenedicarboxylic acid, 1,3-biphenylenedicarboxylic acid, 1,4-biphenylenedicarboxylic acid, 1,5-biphenylenedicarboxylic acid, 1,6-biphenylenedicarboxylic acid, 1,7-biphenylenedicarboxylic acid, 1,8-biphenylenedicarboxylic acid, 2,3-biphenylenedicarboxylic acid, 2,6-biphenylenedicarboxylic acid and 2,7-biphenylenedicarboxylic acid. From the standpoint of the properties of the obtained coating film, 2,6-biphenylenedicarboxylic acid and 2,7-biphenylenedicarboxylic acid are preferable. The above compounds may be used singly or in combination of two or more.
Examples of the dicarboxylic acid having the internal acetylene skeleton structure having the divalent group represented by formula (E) include 4,4xe2x80x2-tolandicarboxylic acid. 3,4xe2x80x2-tolandicarboxylic acid, 3,3xe2x80x2-tolandicarboxylic acid, 2,4xe2x80x2-tolandicarboxylic acid, 2,3xe2x80x2-tolandicarboxylic acid and 2,2xe2x80x2-tolandicarboxylic acid. The above compounds may be used singly or in combination of two or more.
The above tolandicarboxylic acids can be obtained, for example, by preparing stilbene from a derivative of a benzoic acid ester and synthesizing the tolan skeleton structure from the obtained stilbene or by synthesis with introduction of the tolan skeleton structure using a derivative of a benzoic acid ester and a phenylethynyl derivative in accordance with the Heck reaction.
Examples of the dicarboxylic acid having a divalent group selected from the groups represented by formulae (F) include isophthalic acid, terephthalic acid, 4,4xe2x80x2-biphenyldicarboxylic acid, 3,4xe2x80x2-biphenyldicarboxylic acid, 3,3xe2x80x2-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4xe2x80x2-sulfonylbisbenzoic acid, 3,4xe2x80x2-sulfonylbisbenzoic acid, 3,3xe2x80x2-sulfonylbisbenzoic acid, 4,4xe2x80x2-oxybisbenzoic acid, 3,4xe2x80x2-oxybisbenzoic acid, 3,3xe2x80x2-oxybisbenzoic acid, 2,2-bis(4-carboxyphenyl)propane, 2,2-bis(3-carboxyphenyl)propane, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(3-carboxyphenyl)-hexafluoropropane, 2,2xe2x80x2-dimethyl-4,4xe2x80x2-biphenyldicarboxylic acid, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-dimethyl-3,3xe2x80x2-biphenyl-dicarboxylic acid, 2,2xe2x80x2-bis(trifluoromethyl)-4,4xe2x80x2-biphenyldicarboxylic acid, 3,3xe2x80x2-bis(trifluoromethyl)-4,4xe2x80x2-biphenyldicarboxylic acid, 2,2xe2x80x2-bis(trifluoromethyl)-3,3xe2x80x2-biphenyldicarboxylic acid, 9,9-bis(4-(4-carboxy-phenoxy)phenyl)fluorene, 9,9-bis(4-(3-carboxyphenoxy)phenyl)fluorene, 4,4xe2x80x2-bis(4-carboxyphenoxy)biphenyl, 4,4xe2x80x2-bis(3-carboxyphenoxy)biphenyl, 3,4xe2x80x2-bis(4-carboxyphenoxy)biphenyl, 3,4xe2x80x2-bis(3-carboxyphenoxy)biphenyl, 3,3xe2x80x2-bis(4-carboxyphenoxy)biphenyl, 3,3xe2x80x2-bis(3-carboxyphenoxy)biphenyl, 4,4xe2x80x2-bis(4-carboxyphenoxy)-p-terphenyl, 4,4xe2x80x2-bis(4-carboxyphenoxy) -m-terphenyl, 3,4xe2x80x2-bis(4-carboxyphenoxy)-p-terphenyl, 3,3xe2x80x2-bis(4-carboxyphenoxy)-p-terphenyl, 3,4xe2x80x2-bis(4-carboxyphenoxy)-m-terphenyl, 3,4xe2x80x2-bis(4-carboxyphenoxy)-m-terphenyl, 4,4xe2x80x2-bis(3-carboxyphenoxy)-p-terphenyl, 4,4xe2x80x2-bis(3-carboxyphenoxy)-m-terphenyl, 3,4xe2x80x2-bis(3-carboxyphenoxy)-p-terphenyl, 3,3xe2x80x2-bis(3-carboxyphenoxy)-p-terphenyl, 3,4xe2x80x2-bis(3-carboxyphenoxy)-m-terphenyl, 3,3xe2x80x2-bis(3-carboxyphenoxy)-m-terphenyl, 3-fluoroisophthalic acid, 2-fluoroisophthalic acid, 2-fluoroterephthalic acid, 2,4,5,6-tetrafluoroisophthalic acid, 2,3,5,6-tetrafluoroterephthalic acid, 5-trifluoromethylisophthalic acid, 9,9-bis(2-carboxyphenyl)fluorene, 9,9-bis(3-carboxyphenyl)fluorene, 9,9-bis(4-carboxyphenyl)fluorene, bis((2-carboxy-3-phenyl)phenyl)fluorene, bis((4-carboxy-3-phenyl)phenyl)fluorene, bis((5-carboxy-3-phenyl)phenyl)-fluorene, bis((6-carboxy-3-phenyl)phenyl)fluorene, 9,9-bis(4-(2-carboxyphenoxy)phenyl)fluorene, 9,9-bis(4-(3-carboxyphenoxy)phenyl)-fluorene, 9,9-bis(4-(4-carboxyphenoxy)phenyl)fluorene, 9,9-bis((4-(2-carboxyphenoxy)-3-phenyl)phenyl)fluorene, 9,9-bis((4-(3-carboxyphenoxy)-3-phenyl)phenyl)fluorene and 9,9-bis((4-(4-carboxyphenoxy)-3-phenyl)-phenyl)fluorene. The above compounds may be used singly or in combination of two or more.
The hydrogen atoms on the benzene ring in the groups represented by general formulae (A), (B), (C), (D), (E), (F) and (G) may be substituted with at least one atom or group selected from alkyl groups having 1 to 4 carbon atoms, fluorine atom and trifluoromethyl group. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group and t-butyl group.
The precursor of a polybenzoxazole resin of the present invention can be brought into the condensation reaction and the crosslinking reaction by heating and a polybenzoxazole resin can be obtained. In general formula [1] representing the structure in the precursor, m and n represent integers the total of which is 2 to 1,000 and preferably 5 to 100. When the above total exceeds 1,000, viscosity of a varnish prepared by dissolving the precursor is great and handling becomes difficult. Therefore, such a value is not preferable from the standpoint of practical application. m and n satisfy the relation:
0.05xe2x89xa6m/(m+n)xe2x89xa61
and preferably the relation:
0.5xe2x89xa6m/(m+n)xe2x89xa61
The values of m and n satisfying the relation:
(m/m+n) less than 0.05
mean that the number of the repeating unit having the crosslinking group is small and such a structure is not preferable since the number available for the crosslinking is small and heat resistance is not much improved. The repeating units having the crosslinking group and the repeating units having no crosslinking groups may be arranged in a block arrangement or in a random arrangement.
The precursor of a polybenzoxazole resin of the present invention can be produced in accordance with the processes described above. For example, when the precursor of a polybenzoxazole is prepared in accordance with the acid chloride process, dicarboxylic acid and thionyl chloride in an excess amount are reacted at a temperature in the range of the room temperature to about 130xc2x0 C. in the presence of a catalyst such as N,N-dimethylformamide. After the remaining amount of thionyl chloride is removed by heating under a reduced pressure, the residue is recrystallized from a solvent such as hexane and a dicarboxylic acid chloride is prepared. The prepared dicarboxylic acid chloride is dissolved, in general, into a polar solvent such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide in combination with a bisaminophenol compound. The reaction is allowed to proceed in the prepared mixture at a temperature in the range of the room temperature to about xe2x88x9230xc2x0 C. in the presence of an acid acceptor such as pyridine and the precursor of a polybenzoxazole is obtained. In the precursor of a polybenzoxazole resin which is obtained from at least one of the bisaminophenol compounds having a tetravalent group selected from the groups represented by general formulae (A) and at least one of dicarboxylic acid having a divalent group selected from the groups represented by general formulae (B), (C), (D) and (E), the repeating units may be arranged in a block arrangement or in a random arrangement.
In the structure represented by general formula [1], the repeating units having the crosslinking group and the repeating units having no crosslinking groups may be arranged in a block arrangement or in a random arrangement. The structure having the repeating units arranged in a block arrangement can be produced, for example, in accordance with the following acid chloride process. A bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A) and a chloride of a dicarboxylic acid having a divalent group selected from the groups represented by formulae (F) are reacted in advance and the molecular weight is raised. Then, the bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A) and a chloride of a dicarboxylic acid having a structure contributing to crosslinking which is selected from the divalent groups represented by formulae (B), (C), (D) and (E) are reacted.
The order in the above reactions may be reversed. A bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A) and a chloride of a dicarboxylic acid having a structure contributing to crosslinking which is selected from the divalent groups represented by formulae (B), (C), (D) and (E) may be reacted in advance and the molecular weight is raised. Then, the bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A) and a chloride of a dicarboxylic acid having a divalent group selected from the groups represented by formulae (F) may be reacted.
The structure having the repeating units arranged in a random arrangement can be produced by simultaneously reacting a bisaminophenol compound having a tetravalent group selected from the groups represented by formulae (A), a chloride of a dicarboxylic acid having a structure contributing to crosslinking which is selected from the divalent groups represented by formulae (B), (C), (D) and (E) and a chloride of a dicarboxylic acid having a divalent group selected from the groups represented by formulae (F).
In the present invention, the organic solvent used for dissolving the precursor of a polybenzoxazole resin so that the prepared solution can be used as the material for insulating films is different depending on the structure of the dissolved solute. Examples of the organic solvent include propylene carbonate, diacetone alcohol, N-methyl-2-pyrrolidone xcex3-butyrolactone, N,N-dimethylacetamide, dimethylsulfoxide, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol mono-n-butyl ether, propylene glycol diacetate, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, butyl lactate, methyl-1,3-propylene glycol acetate, 1,3-butylene glycol 3-monomethyl ether, methyl pyruvate, ethyl pyruvate and methyl 3-methoxypropionate. The organic solvents may be used singly or in combination of two or more.
The precursor of a polybenzoxazole resin of the present invention is used, for example, in the following manner. A varnish is prepared by dissolving the precursor of a polybenzoxazole resin into a solvent such as N-methyl-2-pyrrolidone and a suitable support such as a silicon wafer or a ceramic base plate is coated with the varnish. Examples of the coating process include the spin coating process using a spinner, the spray coating process using a spray coater, the dipping process, the printing process and the roll coating process. The coated film is dried. Then, the dried coating film is treated by heating so that the solvent is removed, the condensation reaction and the crosslinking reaction take place and the precursor is converted into the polybenzoxazole resin. The obtained film can be used as the insulating film.
The material used for the insulating film of the present invention may further comprise various additives, where necessary. Examples of the additive include coupling agents such as silane coupling agents and radical generators which generate radicals such as oxygen radical and sulfur radical by heating. A photosensitive resin composition can be prepared by using the precursor of a polybenzoxazole in combination with a naphthoquinone diazide compound as the photosensitive agent.
The semiconductor device of the present invention comprises at least one of insulating interlayer films of multi-layer wiring and films for protecting surfaces which comprise the above insulating film comprising the polybenzoxazole resin.
The insulating film of the present invention may be used, for example, as the insulating interlayer films of multi-layer wiring in semiconductor devices. For enhancing adhesion, a semiconductor substrate is coated with an adhesive coating material and an adhesive coating film is formed. Examples of the process for forming the coating film include the spin coating process using a spinner, the spray coating process using a spray coater, the dipping process, the printing process and the roll coating process. The coating film is prebaked at a temperature above the boiling point of the organic solvent so that the organic solvent is removed by vaporization and the coating film is dried and an adhesive coating film is formed.
Then, the adhesive coating film obtained above is coated with the solution of the material for the insulating film of the present invention in accordance with the same process as that conducted above and a laminate structure is formed. A coating film thus formed is prebaked under the same condition as that described above so that the organic solvent is removed by vaporization and the film is dried. After the heat treatment of the film, an insulating interlayer film can be formed.
A film for protecting the surface can be formed by forming a film in accordance with similar procedures.
To summarize the advantages of the present invention, the precursor of a polybenzoxazole resin of the present invention exhibits excellent solubility into organic solvents and, after being converted into the polybenzoxazole resin, excellent properties under heating and is advantageously used for insulating interlayer films and films for protecting surfaces in semiconductors, insulating interlayer films of multi-layer circuits, cover coats of flexible copper clad laminates, solder resist films and liquid crystal-aligning films.